Biomedical subjects

Feng Gao

Publications and source records attributed to Feng Gao.

At least 235 records · Page 13Linked to original sources

PubMed2003

One-step nanocasting synthesis of highly ordered single crystalline indium oxide nanowire arrays from mesostructured frameworks.

A one-step nanocasting route has been demonstrated to prepare highly ordered single-crystal indium oxide nanowire (IONW) arrays with mesostructured frameworks. Unlike the reported multistep nanocasting process (synthesis of mesoporous materials, and then incorporation of precursors and formation of inorganic frameworks), a highly ordered mesostructured surfactant-silica monolith with low external surface serves as both the template and the reducing agent and makes the formation of single-crystal IONWs in its channels easily in one step by using normal In(NO(3))(3) as an inorganic precursor. After silica is removed, highly ordered uniform single-crystal IONW arrays with hexagonal (p6mm) or cubic (Ia3d) mesostructures are derived. These new materials are studied by XRD, SEM, TEM, N(2) adsoption, and UV spectrum. Furthermore, this one-step nanocasting synthesis route is a generalized method and can be used to synthesized a highly ordered mesoporous silica monolith with metal oxide nanocrystals in its channels. To the best of our knowledge, this is the first report of a single crystalline mesostructured In(2)O(3) framework.

Journal Article↗

PubMed2003

Low-temperature synthesis of titanium disulfide nanotubes.

A low-temperature gas reaction was used to successfully synthesize TiS2 nanotubes with an outer diameter of approximately 20 nm, an inner diameter of approximately 10 nm, an interlayer spacing of approximately 0.57 nm, and an average length of 2-5 microm.

Journal Article↗

PubMed2003

Viremia control despite escape from a rapid and potent autologous neutralizing antibody response after therapy cessation in an HIV-1-infected individual.

The neutralizing Ab response after primary HIV-1 infection is delayed relative to the virus-specific CD8(+) T cell response and the initial decline in plasma viremia. Because nearly all HIV-1 infections result in AIDS, it would be instructive to study cases where neutralizing Ab production commenced sooner. This was done in subject AC10, an individual treated during early infection and in whom a rapid autologous neutralizing Ab response was detected after therapy cessation as rebound viremia declined and remained below 1000 RNA copies/ml of blood for over 2.5 years. This subject's Abs were capable of reducing the infectivity of his rebound virus by >4 logs in vitro at a time when rebound viremia was down-regulated and virus-specific CD8(+) T cells were minimal, suggesting that neutralizing Abs played an important role in the early control of viremia. The rebound virus did not exhibit an unusual phenotype that might explain its high sensitivity to neutralization by autologous sera. Neutralization escape occurred within 75 days and was proceeded by neutralizing Ab production to the escape variant and subsequent escape. Notably, escape was not associated with a significant rise in plasma viremia, perhaps due to increasing CD8(+) T cell responses. Sequence analysis of gp160 revealed a growing number of mutations over time, suggesting ongoing viral evolution in the face of potent antiviral immune responses. We postulate that an early effective neutralizing Ab response can provide long-term clinical benefits despite neutralization escape.

Adult↗

PubMed2003

Sexual behavior of HIV discordant couples after HIV counseling and testing.

BACKGROUND AND OBJECTIVES: Sexual behavior following voluntary HIV counseling and testing (VCT) is described in 963 cohabiting heterosexual couples with one HIV positive and one HIV negative partner ('discordant couples'). Biological markers were used to assess the validity of self-report. METHODS: Couples were recruited from a same-day VCT center in Lusaka, Zambia. Sexual exposures with and without condoms were recorded at 3-monthly intervals. Sperm detected on vaginal smears, pregnancy, and sexually transmitted diseases (STD) including HIV, gonorrhea, syphilis, and Trichomonas vaginalis were assessed. RESULTS: Less than 3% of couples reported current condom use prior to VCT. In the year after VCT, > 80% of reported acts of intercourse in discordant couples included condom use. Reporting 100% condom use was associated with 39-70% reductions in biological markers; however most intervals with reported unprotected sex were negative for all biological markers. Under-reporting was common: 50% of sperm and 32% of pregnancies and HIV transmissions were detected when couples had reported always using condoms. Positive laboratory tests for STD and reported extramarital sex were relatively infrequent. DNA sequencing confirmed that 87% of new HIV infections were acquired from the spouse. CONCLUSIONS: Joint VCT prompted sustained but imperfect condom use in HIV discordant couples. Biological markers were insensitive but provided evidence for a significant under-reporting of unprotected sex. Strategies that encourage truthful reporting of sexual behavior and sensitive biological markers of exposure are urgently needed. The impact of prevention programs should be assessed with both behavioral and biological measures.

Adult↗

PubMed2003

Posttransplant administration of allochimeric major histocompatibility complex class-I-molecules induces true transplantation tolerance.

BACKGROUND: Allochimeric class-I major histocompatibility complex (MHC) molecules that contain donor-type immunogenic epitopes displayed on recipient-type sequences were shown to induce transplantation tolerance when administered at the time of transplantation. Here, we investigated the ability of posttransplant allochimeric administration to induce tolerance and concomitantly inhibit chronic rejection. METHODS: Allochimeric (alpha1h(1/u))-RT1.Aa class-I MHC antigenic extracts were administered by way of the portal vein into ACI recipients of Wistar-Firth (WF) hearts at days +3, +7, and +10 posttransplantation in conjunction with subtherapeutic oral cyclosporine. RESULTS: Delayed posttransplant allochimeric administration induced donor-specific transplantation tolerance to rat cardiac allografts. In contrast, delayed delivery of unaltered donor- or recipient-type MHC extracts failed to prolong allograft survival. In addition, histopathologic examination or estimation of transplant vascular sclerosis by neointimal index assessment, following delayed allochimeric therapy, revealed intact global architecture and minimal intimal thickening, respectively. CONCLUSION: Allochimeric MHC class-I therapy is a unique and novel clinically applicable approach for induction of "true" transplantation tolerance where chronic rejection is concomitantly abrogated.

Animals↗

PubMed2003

Crystallization and preliminary crystallographic analysis of extracellular fragment X3 of YWK-II/APPH: a human sperm membrane protein related to the Alzheimer betaA4-amyloid precursor protein.

Crystals of extracellular fragment X3 of a human sperm membrane protein YWK-II/APPH have been grown at 291 K using 8% PEG 4000 as precipitant by the vapour-diffusion method. The diffraction pattern of the crystal extends to 2.9 A resolution at 100 K using Cu Kalpha radiation in-house. The crystals belong to space group P2(1), with unit-cell parameters a = 46.0, b = 43.7, c = 90.2 A, alpha = gamma = 90.0, beta = 106.6 degrees. Furthermore, a selenomethionine (SeMet) derivative of the protein was overexpressed in the same expression system and was purified in a reducing environment. The derivative crystals were obtained under similar conditions. Subsequently, a single-wavelength data set was collected to 2.38 A resolution from the derivative crystal at ESRF. The crystals belong to space group P2(1), with unit-cell parameters a = 46.2, b = 44.0, c = 88.3 A, alpha = gamma = 90.0, beta = 103.6 degrees. The presence of one molecule per asymmetric unit gives a crystal Volume per protein mass (V(M)) of 2.8 A(3) Da(-1) and a solvent content of 56.4% by Volume.

Amyloid beta-Protein Precursor↗

PubMed2003

Crystallization and preliminary X-ray crystallographic analysis of the trimer core from measles virus fusion protein.

Two heptad-repeat regions (HR1 and HR2) are highly conserved in paramyxovirus fusion proteins and form a stable helical trimer of heterodimers [(HR1-HR2)(3)] after the fusion between viral and cellular membranes. In this study, two HR regions of the fusion protein of measles virus, a member of the paramyxoviruses, were selected and overexpressed as a single chain (named 2-Helix) connected by an amino-acid linker using a GST-fusion expression system in Escherichia coli. Crystals of 2-Helix protein (GST removed) could be obtained from many conditions using the sitting- or hanging-drop vapour-diffusion method. A complete data set was collected in-house to 1.9 A resolution from a single crystal. The crystal belongs to space group P6, with unit-cell parameters a = b = 51.637, c = 67.058 A. To facilitate the crystal structure solution, SeMet-substituted 2-Helix crystals, grown under similar conditions to the native, were also obtained and diffracted X-rays to 1.8 A using synchrotron radiation.

Crystallization↗

PubMed2003

Analysis of the nonsteroidal anti-inflammatory drug literature for potential developmental toxicity in rats and rabbits.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed to pregnant women. Some case-control studies have linked the NSAIDs aspirin and indomethacin with a risk of congenital abnormalities and low birthweight. High doses of aspirin produce developmental toxicity in rats (e.g., gastroschisis/umbilical hernia, diaphragmatic hernia [DH]) when administered during sensitive windows of development. Unlike other NSAIDs, aspirin irreversibly inhibits cyclooxygenases (COXs) 1 and 2. Hence, the developmental toxicity seen in rats after exposure to aspirin may be due to the irreversible inhibition of COX-1 and/or COX-2. If so, other NSAIDs, which act through a reversible inhibition of COX, may produce a weak developmental toxicity signal or no developmental toxicity signal when tested in preclinical models. To investigate this relationship, a comprehensive analysis of the NSAID developmental toxicity literature was undertaken to determine whether NSAIDs other than aspirin induce developmental anomalies similar to those elicited by aspirin. METHODS: Developmental toxicity studies were identified through literature searches of PubMed and TOXNET, and pregnancy outcome data were extracted and tabulated. By using a set of defined criteria, each study was evaluated for quality and assigned to one of five tiers. The relation between certain malformations and NSAID treatment was analyzed for the best studies (tiers 1-4) by using concurrent control data (Mantel-Haenszel and permutation tests) and by combining the concurrent control data with historical control data (chi2 test and permutation tests). RESULTS: A qualitative analysis of these data led to a focus on three types of malformations: DH, ventricular septal defects (VSDs), and midline defects (MDs). In rats, the incidences of VSD and MD were increased among fetuses treated with NSAIDs when compared with the concurrent controls. The extent of the increase was attenuated when the data from the aspirin studies were excluded from the analysis. There were no qualifying (i.e., tiers 1-4) aspirin studies conducted in rabbits, but the incidences of the three defects were increased over control incidences among non-aspirin NSAID-treated animals. Statistical analysis of these data was subsequently conducted. When tiers 1-4 were combined and compared with concurrent controls plus the most appropriate historical control database, the strongest associations were between NSAID treatment and VSD in rats, VSD in rabbits, and MD in rabbits. There also was some suggestion of an association between NSAID treatment and DH in rabbits. CONCLUSIONS: This analysis of the non-clinical NSAID literature demonstrated a possible association between exposure to NSAIDs and developmental anomalies. The anomalies were similar for aspirin and for other NSAIDs, but effects occurred at a much lower incidence with non-aspirin NSAIDs than previously reported with aspirin. Such a finding is consistent with the concept that reversible inhibition of COX-1 and/or COX-2 by other NSAIDs would produce weaker developmental toxicity signals than aspirin. However, there were limitations of the evaluated studies: (1) there were very few robust International Conference on Harmonization-compliant studies conducted with NSAIDs in the published literature; (2) many of the studies were conducted at doses well below the maximum tolerated dose (MTD), where effects are rarely seen; and (3) numerous studies were conducted above the MTD, where reduced numbers of fetuses hampered detection of low-incidence findings. Although weak associations were observed, these limitations prevented us from definitively determining the presence or absence of a developmental toxicity signal from the existing body of NSAID data. Further exploration of this hypothesis will require assessing the potential association in animal models by using dose levels centered around the MTD.

Abnormalities, Drug-Induced↗

PubMed2003

Estimation of the optimal electrophoretic temperature of DNA single-strand conformation polymorphism by DNA base composition.

To explore the relation between DNA base composition and the optimal single-strand conformation polymorphism (SSCP) electrophoretic temperature (T(s)), we analyzed DNA base composition and T(s) of 24 DNA fragments from different genes and found that T(s) was positively correlative with the ratio of base C/base A. T(s) could be estimated by the formula T(s) = [80 x C/(A+1)]/[2.71 + [C/(A+1)]]. T(s) could be increased dramatically by the complementary sequences in both 5'-and 3'-ends of a DNA single-strand.

Base Composition↗

PubMed2003

Cytoprotective and antiapoptotic effects of IL-13 in hepatic cold ischemia/reperfusion injury are heme oxygenase-1 dependent.

Liver injury caused by ischemia/reperfusion (I/R) insult represents the major problem following orthotopic liver transplantation (OLT). I/R damage has been linked to Th1-like cytokine producers. This study evaluates putative cytoprotective effects/mechanisms of Th2-type IL-13 gene transfer. IL-13 overexpression prevented hepatic insult in a rat model of 24 h cold ischemia followed by OLT, as assessed: (i) profoundly decreased hepatocellular damage (sGOT levels), and ameliorated histological signs of I/R injury (Suzuki criteria), consistent with long-term OLT survival; (ii) prevented hepatic apoptosis (TUNEL stains) and up-regulated expression of antiapoptotic (A20, Bcl-2/Bcl-xl)/antioxidant (HO-1) genes. However, inhibition of HO-1 with tin protoporphyrin reversed cytoprotective/antiapoptotic effects of IL-13. In conclusion, cytoprotection rendered by virally induced IL-13 against hepatic I/R injury in this clinically relevant rat hepatic cold I/R injury model was accomplished via decreased apoptosis and induction of antiapoptotic/antioxidant molecules. HO-1 neutralization studies suggest that HO-1 represents one of putative IL-13 downstream effectors. This study provides the rationale for novel approaches to maximize organ donor pool through the safer use of OLTs despite prolonged periods of cold ischemia.

Animals↗

PubMed2003

Helicobacter pylori stimulates host cyclooxygenase-2 gene transcription: critical importance of MEK/ERK-dependent activation of USF1/-2 and CREB transcription factors.

Cyclooxygenase-2 (COX-2) represents the inducible key enzyme of arachidonic acid metabolism and contributes to the pathogenesis of gastroduodenal ulcers and gastric cancer. Helicobacter pylori infection is associated with elevated gastric COX-2 levels, but the mechanisms underlying H. pylori-dependent cox-2 gene expression are unclear. H. pylori stimulated cox-2 mRNA and protein abundance in gastric epithelial cells in vitro and in vivo, and functional analysis of the cox-2 gene promoter mapped its H. pylori-responsive region to a proximal CRE/Ebox element at -56 to -48. Moreover, USF1/-2 and CREB transcription factors binding to this site were identified to transmit H. pylori-dependent cox-2 transcription. Activation of MEK/ERK1/-2 signalling by bacterial virulence factors located outside the H. pylori cag pathogenicity island (cagPAI) was found to mediate bacterial effects on the cox-2 promoter. Our study provides a detailed description of the molecular pathways underlying H. pylori-dependent cox-2 gene expression in gastric epithelial cells, and may thus contribute to a better understanding of mechanisms underlying H. pylori pathogenicity.

Animals↗

PubMed2003

Stat4 and Stat6 signaling in hepatic ischemia/reperfusion injury in mice: HO-1 dependence of Stat4 disruption-mediated cytoprotection.

Ischemia/reperfusion (I/R) injury remains an important problem in clinical organ transplantation. There is growing evidence that T lymphocytes, and activated CD4+ T cells in particular, play a key role in hepatic I/R injury. This study analyzes the role of signal transducer and activator of transcription 4 (Stat4) and Stat6 signaling in liver I/R injury. Using a partial lobar warm ischemia model, groups of wild-type (WT), T cell-deficient, Stat4-/Stat6-deficient knockout (KO) mice were assessed for the extent/severity of I/R injury. Ninety minutes of warm ischemia followed by 6 hours of reperfusion induced a fulminant liver failure in WT and Stat6 KO mice, as assessed by hepatocellular damage (serum alanine aminotransferase [sALT] levels), neutrophil accumulation (myeloperoxidase [MPO] activity) and histology (Suzuki scores). In contrast, T cell deficiency (nu/nu mice) or disruption of Stat4 signaling (Stat4 KO mice) reduced I/R insult. Unlike adoptive transfer of WT or Stat6-deficient T cells, infusion of Stat4-deficient T cells failed to restore hepatic I/R injury and prevented tumor necrosis factor alpha (TNF-alpha) production in nu/nu mice. Diminished TNF-alpha/Th1-type cytokine messenger RNA (mRNA)/protein elaborations patterns, along with overexpression of heme oxygenase-1 (HO-1)-accompanied hepatic cytoprotection in Stat4 KO recipients. In contrast, HO-1 depression restored hepatic injury in otherwise I/R resistant Stat4 KOs. In conclusion, Stat4 signaling is required for, whereas Stat4 disruption protects against, warm hepatic I/R injury in mice. The cytoprotection rendered by Stat4 disruption remains HO-1-dependent.

Adoptive Transfer↗

PubMed2003

Codon usage optimization of HIV type 1 subtype C gag, pol, env, and nef genes: in vitro expression and immune responses in DNA-vaccinated mice.

Codon usage optimization of human immunodeficiency virus type 1 (HIV-1) structural genes has been shown to increase protein expression in vitro as well as in the context of DNA vaccines in vivo; however, all optimized genes reported thus far are derived from HIV-1 (group M) subtype B viruses. Here, we report the generation and biological characterization of codon usage-optimized gag, pol, env (gp160, gp140, gp120), and nef genes from a primary (nonrecombinant) HIV-1 subtype C isolate. After transfection into 293T cells, optimized subtype C genes expressed one to two orders of magnitude more protein (as determined by immunoblot densitometry) than the corresponding wild-type constructs. This effect was most pronounced for gp160, gp140, Gag, and Pol (>250-fold), but was also observed for gp120 and Nef (45- and 20-fold, respectively). Optimized gp160- and gp140-derived glycoproteins were processed, incorporated into virus particles, and mediated virus entry when expressed in trans to complement an env-minus HIV-1 provirus. Mice immunized with optimized gp140 DNA developed antibody as well as CD4+ and CD8+ T cell immune responses that were orders of magnitude greater than those of mice immunized with wild-type gp140 DNA. These data confirm and extend previous studies of codon usage optimization of HIV-1 genes to the most prevalent group M subtype. Our panel of matched optimized and wild-type subtype C genes should prove valuable for studies of protein expression and function, the generation of subtype-specific immunological reagents, and the production of DNA-based sub-unit vaccines directed against a broader spectrum of viruses.

AIDS Vaccines↗

PubMed2003

Design and analysis of post-fusion 6-helix bundle of heptad repeat regions from Newcastle disease virus F protein.

Fusion of paramyxovirus to the cell involves receptor binding of the HN glycoprotein and a number of conformational changes of F glycoprotein. The F protein is expressed as a homotrimer on the virus surface. In the present model, there are at least three conformations of F protein, i.e. native form, pre-hairpin intermediate and the post-fusion state. In the post-fusion state, the two highly conserved heptad repeat (HR) regions of F protein form a stable 6-helix coiled-coil bundle. However, no crystal structure is known for this state for the Newcastle disease virus, although the crystal structure of the F protein native form has been solved recently. Here we deployed an Escherichia coli in vitro expression system to engineer this 6-helix bundle by fusion of either the two HR regions (HR1, linker and HR2) or linking the 6-helix [3 x (HR1, linker and HR2)] together as a single chain. Subsequently, both of them form a stable 6-helix bundle in vitro judging by gel filtration and chemical cross-linking and the proteins show salient features of an alpha-helix structure. Crystals diffracting X-rays have been obtained from both protein preparations and the structure determination is under way. This method could be used for crystallization of the post-fusion state HR structures of other viruses.

Amino Acid Sequence↗

PubMed2003

Inhibition of IkappaB kinase by a new class of retinoid-related anticancer agents that induce apoptosis.

The transcription factor NF-kappaB is overexpressed or constitutively activated in many cancer cells, where it induces expression of antiapoptotic genes correlating with resistance to anticancer therapies. Small molecules that inhibit the NF-kappaB signaling pathway could therefore be used to induce apoptosis in NF-kappaB-overexpressing tumors and potentially serve as anticancer agents. We found that retinoid antagonist MX781 inhibited the activation of NF-kappaB-dependent transcriptional activity in different tumor cell lines. MX781 was able to completely inhibit tumor necrosis factor alpha-mediated activation of IkappaB kinase (IKK), the upstream regulator of NF-kappaB. Inhibition of IKK activity resulted from direct binding of MX781 to the kinase, as demonstrated by in vitro inhibition studies. Two other molecules, MX3350-1 and CD2325, which are retinoic acid receptor gamma-selective agonists, were capable of inhibiting IKK in vitro, although they exerted variable inhibition of IKK and NF-kappaB activities in intact cells in a cell type-specific manner. However, N-(4-hydroxyphenyl)-retinamide, another apoptosis-inducing retinoid, and retinoic acid as well as other nonapoptotic retinoids did not inhibit IKK. Inhibition of IKK by the retinoid-related compounds and other small molecules correlated with reduced cell proliferation and increased apoptosis. Reduced cell viability was also observed after overexpression of an IKKbeta kinase-dead mutant or the IkappaBalpha superrepressor. The induction of apoptosis by the retinoid-related molecules that inhibited IKK was dependent on caspase activity but independent of the retinoid receptors. Thus, the presence of an excess of retinoic acid or a retinoid antagonist did not prevent the inhibition of IKK activation by MX781 and CD2325, indicating a retinoid receptor-independent mechanism of action.

Antineoplastic Agents↗

PubMed2003

Determination of enantiomeric excess using the ultraviolet-circular dichroism and the high-performance liquid chromatography-circular dichroism methods.

Two useful numerical methods using ultraviolet (UV) and circular dichroism (CD) spectroscopies are proposed to determine enantiomeric excess (e.e). An algorithm is also proposed to generate self-consistent pure R and S enantiomer reference spectra. After all pure reference spectra are generated, a simulated annealing algorithm is applied to minimize the mismatch between the experimental spectra and the spectra after a least-squares fit. Optimal factors for R and S enantiomers are then used to determine e.e. The ultraviolet-circular dichroism (UV-CD) method uses the combined UV and CD spectra in a composite form, while the high-performance liquid chromatography (HPLC)-CD method only employs the CD spectra with the total concentrations of R plus S enantiomers provided by HPLC using a non-chiral stationary phase. Both methods were successfully tested on mixtures with known composition and then applied to real experimental data (unknown compositions). Compared with the UV-CD method, the results show that excellent results are more readily obtained using the HPLC-CD method. With the systems studied, the latter usually provided outstanding estimations of e.e with low error percentages.

Algorithms↗

PubMed2003

Repression of allo-cell transplant rejection through CIITA ribonuclease P+ hepatocyte.

AIM: Allo-cell transplant rejection and autoimmune responses were associated with the presence of class II major histocompatibility complex (MHC II) molecules on cells. This paper studied the effect of Ribonuclease P (RNase P) against CIITA, which was a major regulator of MHCII molecules, on repressing the expression of MHCII molecules on hepatocyte. METHODS: M1-RNA is the catalytic RNA subunit of RNase P from Escherichia coli. It were constructed that M1-RNA with guide sequences (GS) recognizing the 452, 3408 site of CIITA by PCR from pTK117 plasmid, then were cloned into the EcoRI/BglII or EcoR//SalIsite of vector psNAV (psNAV-M1-452-GS, psNAV-M1-3408-GS) respectively. The target mould plate (3176-3560) of CIITA was obtained from Raji cell by RT-PCR, and then inserted into the XhoI/EcoRIof pGEM-7zf(+) plasmid (pGEM-3176). These recombinant plasmids were screened out by sequence analysis. psNAV-M1-452-GS, psNAV-M1-3408-GS and its target RNA pGEM-3176 were transcribed and then mixed up and incubated in vitro. It showed that M1-3408-GS could exclusively cleave target RNA that formed a base pair with the GS. Stable transfectants of hepatocyte cell line with psNAV-M1-3408-GS were tested for expression of class II MHC through FCM, for mRNA abundance of MHCII, Ii and CIITA by RT-PCR., for the level of IL-2 mRNA on T cell by mixed lymphocyte reaction. RESULTS: When induced with recombinant human interferon-gamma (IFN-gamma), the expression of HLA-DR, -DP, -DQ on psNAV-M1-3408-GS(+) hepatocyte was reduced 83.27 %, 88.93 %, 58.82 % respectively, the mRNA contents of CIITA, HLA-DR, -DP, -DQ and Ii decreased significantly. While T cell expressed less IL-2 mRNA in the case of psNAV-M1-3408-GS(+) hepatocyte. CONCLUSION: The Ribonuclease P against CIITA-M1-3408-GS could effectively induce antigen-specific tolerance through cleaving CIITA. These results provided insight into the future application of M1-3408-GS as a new nucleic acid drug against allo-transplantation rejection and autoimmune diseases.

Base Sequence↗

PubMed2003

[Effects of glucose-insulin-potassium cocktail on cardiac myocyte death and post-ischemic recovery cardiac functional recovery: the critical role of insulin].

OBJECTIVE: To study the effect of glucose-insulin-potassium (GIK) cocktail on cardiac myocyte death (i.e., necrosis and apoptosis) and cardiac functional recovery following myocardial ischemia/reperfusion (MI/R), and to further investigate the role of insulin in the GIK-induced cardioprotective effect. METHODS: Male Sprague-Dawley rats were subjected to 30 min myocardial ischemia followed by reperfusion for 4 h (for cardiac function and cardiomyocyte apoptosis study) or 6 h (for myocardial infarction measurement). Anesthetized rats were randomly treated with continuous infusions of saline, GIK (Glucose: 200 g/L, Insulin: 60 U/L and KCl: 60 mmol/L), GK or insulin at 4 ml.kg(-1).h(-1), beginning 5 min before reperfusion and continuing through the 4-h reperfusion. Arterial blood pressure, ECG and left ventricular pressure were monitored throughout the experiment. Myocardial DNA fragmentation and myocardial infarction were determined at the end of reperfusion. RESULTS: MI/R caused significant cardiac dysfunction and myocardial death (both necrosis and strong DNA ladder formation). Compared with the vehicle treated rats, the GIK-treated rats showed protection against MI/R injury as evidenced by reduced myocardial infarction [(41.3 +/- 8.3)% vs. (54.4 +/- 10.4)% of vehicle, P < 0.05, n = 10], marked decrease of DNA fragmentation, and improved recovery of cardiac systolic/diastolic function at the end of reperfusion [left ventricular developed pressure: (94 +/- 6) mm Hg vs. (86 +/- 5) mm Hg of vehicle, P < 0.05; +LVdP/dt(max): (2 940 +/- 114) mm Hg/s vs. (2 733 +/- 132) mm Hg/s, P < 0.05; -LVdP/dt(max): (2 629 +/- 156) mm Hg/s vs. (2 463 +/- 133) mm Hg/s, P < 0.05]. Insulin exerted the similar cardioprotective effects with GIK; whereas the rats receiving GK failed to show any significant, cardioprotection against MI/R injury. CONCLUSIONS: GIK exerts cardioprotective effect against postischemic myocardial injury. Insulin, mainly through its anti-apoptotic effect, plays a critical role in the GIK-elicited myocardial protection in MI/R.

Animals↗